Boresight alignment device

ABSTRACT

A means for zeroing a small caliber weapon on a target at night without firing the weapon. The means comprises using a boresight alignment light emitting a continuous infrared light that is mounted on a tapered mandrel with the mandrel inserted into the muzzle end of the weapon, an aiming light mounted on the weapon emitting intermittent pulses of infrared light, and a night viewing scope head worn by the weapon operator. The operator zeros the weapon on the target by superimposing the continuous and intermittent pulses of light onto each other. The operator aligns both lights by adjustment screws on the housings of the boresight alignment light and the aiming light.

3 37879693 United States Patent [1 1 1 Stone BORESIGHT ALIGNMENT DEVICE [75] Inventor: Robert L. Stone, Oxon Hill, Md.

[73] Assignee: The United States of America as represented by the Secretary of the Army, Washington, DC.

22 Filed: Dec. 14, 1972 211 App]. No.: 315,064

[52] US. Cl. 250/330, 356/153 [51] Int. Cl. G0lt 1/16 [58] Field of Search 250/833 H, 83.3 HP, 330;

3,067,330 12/1962 Hammar Jan. 22, 1974 Primary Examiner-James W. Lawrence Assistant Examiner-Davis L. Willis Attorney, Agent, or FirmEdward J. Kelly; Herbert Berl; Max L. Harwell [5 7] ABSTRACT A means for zeroing a small caliber weapon on a target at night without firing the weapon. The means comprises using a boresight alignment light emitting a continuous infrared light that is mounted on a tapered mandrel with the mandrel inserted into the muzzle end of the weapon, an aiming light mounted on the weapon emitting intermittent pulses of infrared light, and a night viewing scope head worn by the weapon operator. The operator zeros the weapon on the target by superimposing the continuous and intermittent pulses of light onto each other. The operator aligns both lights by adjustment screws on the housings of the boresight alignment light and the aiming light.

5 Claims, 3 Drawing Figures Pmmmmz a 787 693 SHEU 1 0F 3 I 4 v 1 BORESIGI-IT ALIGNMENT DEVICE BACKGROUND AND SUMMARY OF THE INVENTION Only in the last few years has work been done in the field of night viewing by intensification of ambient light, such as starlight or moonlight, when used with military weapons. The present invention is a method of zeroing an aiming light that is attached to a small caliber weapon with a boresight alignment light that is inserted in the muzzel end of the weapon in which the weapon does not have to be fired, and thus disclose its position.

This invention comprises a method of zeroing the weapon by utilizing a boresight alignment light device that is attached to a tapered mandrel with the mandrel inserted into the muzzle end of the weapon and the boresight alignment light device emitting a continuous collimated beam of infrared light toward the target. An aiming light is attached to the weapon has a pulsing infrared light aimed at the target. The continuous and pulsed infrared lights are adjusted so that their returned illumination is superimposed over each other. This beam from the boresight alignment light is adjusted by means of external boresight adjustment screws connected to an internal mechanism so that when the mandrel is rotated through 360 within the muzzle of the weapon the beam is coaxially concentric with the weapon bore. The aiming light has the same infrared light emission system as the boresight alignment device that the light is intermittent so'that its beam may be distinguished from the continuous beam from the boresight alignment light. The aiming light also has external adjustment screws connected to an internal mechanism for aligning the intermittent infrared beam onto the target. Both the aiming light beam and the boresight alignment light beam are projected in a spectral range invisible to the naked eye but clearly visible with a head worn night viewing scopes.

BRIEF DESCRIPTION THE DRAWINGS FIG. I shows the boresight light housing with attached mandrel and battery power supply;

FIG. 2 illustrates a sectional view of the boresight alignment light; and

FIG. 3 illustrates the aiming light as mounted'on the weapon. 1

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. I illustrates the boresight alignment light device 16 having typical tapered mandrel 12 attached thereto. A plurality of mandrels are provided with device 16 that have different bore diameters for fitting into the muzzle end 18 of different caliber weapons. A battery power supply 14 is shown disattached from light 16 but ready for connection thereto by weather proof connector l threadably connecting the two sections 9a and 9b together. Power supply 14 willbe explained in more detail later in this description.

FIG. 2 is a sectional view of device 16 illustrating the various elements therein and the external connections thereto. Numerals 20 and 22 represent the main housing. Numeral 20 represents the front window and primary mirror retainer and numeral 22 represents the secondary mirror retainer with both retainers being threadably connected together by threads 22a for enclosing weather proof seal 21a to form main housing 16. The transparent front window 27, onto which primary mirror 38 is attached, is held by window retainer ring 28 threadably connected to housing 20. The optical system comprises a catadioptic system mounted inside device 16 which is mounted with its optical axis along the longitudinal axis of 16. That is, primary mirror 38 and a secondary mirror 46 are mounted along the longitudinal axis of device 16 and form an integral part of retainer 20. Mirror 46 is fixedly attached to retainer 20 along the outer circumferential edge 20a. Secondary mirror 46 has an opening in its center for allowing illumination from battery powered diode 42, suchas a gallium arsenide phosphide diode, to pass therethrough and be reflected off primary mirror 38, be re-reflected off the curved portion of secondary mirror 46, and out transparent window 27 in a collimated beam. The collimated beam has only one-fourth degree beam spread. This illumination is shown by dashed lines 42a and 42b with direction arrows attached thereto.

Diode 42 is positioned with its beam along the longitudinal axis of device 16 and isheld by diode mounting plate 24 within diode container 40. Plate 24 is held loosely against housing 22 by three lock screws 44 (with only one shown). Lockscrews 44 are threadably connected to diode mounting plate retainer 32. A diode lock nut 26a is threadably connected on the rear side of diode 42 to hold diode 42 stationary within container 40. Lock nut 26a is tightened down on diode 42 when the diode has been properly focussed by the catadioptic optical system and need not be'removed until the diode is replaced. A seal screw 36 is threadably connected to housing 22 with a proper seal to allow removal when replacement of the diode or refocus thereof is necessary. Oneiof a plurality of tapered mandrels form an integral part of a mandrel adapter 30. Adapter 30 is threadably connected to main housing 22, and when fully threaded is firmly secured thereto. Tapered mandrel 12 is made of hardened steel that is chrome plated. Enlarged portion 12a of mandrel 12 is secured within mandrel adapter 20. Smaller portion 12b is tapered slightly, at about 0.002 inch per foot, to fit into the muzzle end of a weapon whose boresight is being aligned."

The diode 42 is energized power supply 14 thereto through cables 9a and 9b conductively connected together by weather proof connector 10. In FIG. 2', only a portion of cable 9a is shown since FIG. 1 illustratesthe-overall view of these connections. Cable 9 is attachedto retainer 22 at cable connector 13. Conductive leads from cable 9a pass through retainer 22 and are connected to diode 42 at positive terminal 8b and negative terminal 8a. Two large headed knurled boresight adjustment screws 50 (with only one shown) are orthogonally fitted against diode mounting plate 24. On opposite sides of plate 24 from screws 50 are spring loadedplungers 51 (with only one shown). With diode 42 held securely in 40 by lock nut 26a and container 40 attached to plate 24, screws 50 will move plate 24 along two orthogonal axes for projecting the illumination pattern of diode 42 along the longitudinal axis of the boresight alignment device 16. i

FIG. 3 illustrates the aiming light 16a mounted on weapon as used in conjunction with device vl6 mounted on muzzle 18. Device 16 is notshown in FIG.

by connecting battery I 3 since it was explained with reference to FIG. 1. Aiming light 160 is mounted on bracket 62 by bolt 68 pulling the housing of aiming light 16a down in the groove of bracket 62. A dead man switch 60 strapped on the handle of weapon 70 is used to switch an internal battery to a thermal relay. Switch 60 is electrically connected by lead 60a between the battery and thermal relay within the housing of 16a. Switch 60 is positioned on the handle so that it may easily be depressed by the operators trigger finger prior to the operator squeezing the trigger. The internal mechanism of 16a is the same as that of 16 except that battery is internal and the thermal relay has been added in the line between the battery and the gallium arsenide phosphide diode. The thermal relay provides intermittent interruptions between the battery and the diode. Two adjustment screws 50a, positioned orthogonal to each other (with only one shown), align the illumination pattern of the diode along the longitudinal axis of the aiming light 16a in the same manner that adjustment screws 50 in the boresight alignment light device. The weapon is generally zeroed on a target about 100 yards or less from the weapon. Thus, essentially no parallax exists between the two lights. As stated above, the night viewing scope is worn by the operator for receiving the infrared reflections from a target.

In operation of zeroing weapon 70 at night, the boresight alignment light 16 with the tapered mandrel 12 attached thereto is attached to the weapon with the mandrel inserted in the muzzle end 18 of weapon 70. The aiming light is mounted on weapon 70. The weapon operator puts the night viewing scope on his head to view the infrared light from device 16 and light 16a that is reflected from a target.

Diode 42 produces a continuous beamof infrared illumination that is transmitted out of device 16 by way of mirrors 38 and 46 which are suitably curved and spaced to allow a collimated beam of not more than l/4 degree spread. A night viewing scope, or image intensifier, which may be head worn or tripod mounted, receives the reflected illumination from the target, giving the user a visible image of both the scene and the apparent illuminated spot reflected from the point indicating the strike of the bullet. To properly zero the weapon with the target, the borsi ght alignment light 16 is rotated through 360 while both screws 50 are adjusted to position the radiation from diode 42 along the longitudinal axis of device 16 until radiation from diode 42 is positioned along the longitudinal axis of device 16. The reflected spot of illumination from the target will be observed through the night viewing scope to make a sweeping arc while device 16 is rotated through the 360. When the radiation pattern is along the longitudinal axis of device 16, the reflected spot of illumination will be stationary.

The catadioptic optical system comprising primary mirror 38 and secondary mirror 46 has a diameter of 50 millimeters with a one quarterof a degree beam spread, thus forming a relatively small spot of illumination at the target 100 yards away. The size of the spot is also determined by the resolution of the night viewing scope. The gallium arsenide phosphide diode produces illumination in the infrared spectrum, which is invisible to the naked eye. Therefore, the night viewing scope is the type that converts infrared to visible illumination. v

Another illumination source suitable for replacing diode 42 is a Xenon arc lamp with the catadioptic optical system replaced by a simple double convex projection lens. The method of alignment would be the same as described above but with the advantage of the device being smaller and having a narrower beam of illumination. The power source for either device is separated from the boresight alignment device 16, for safety reasons. lf power supply source 14 is allowed to hang or swing while the alignment procedures are in process, the operator is more likely to be reminded to remove device 16 from the muzzle end of the weapon before firing. I

l Claim: 1. A means of zeroing a small caliber weapon at night without firing the weapon, the stepscomprising:

mounting an aiming light on said weapon, said aiming light has an intermittent pulse producing infrared source that produces intermittent beam of infrared illumination and optics that projects said intermittent beam of infrared illumination toward a target; inserting a tapered mandrel having a boresight alignment light mounted thereto into the muzzle end of said weapon, said boresight alignment light has a continuous infrared emitting source that produces a continuous beam of infrared illumination and optics that projects said continuous beam of infrared illuminations toward the same target; providing night viewing image intensifier goggles that are head worn by an operator wherein said goggles convert the intermittent and continuous beams of infrared illumination that is reflected from a target to visible illumination for observationby said operators; rotating said tapered mandrel through 360 within the muzzle end of said weapon and simultaneously adjusting the continuous beam of infrared illumination into a spot of reflected light signifying said continuous beam of light along the boresight of said weapon; and adjusting the direction of said intermittent beamof infrared light until said intermittent beam and said continuous beam are superimposed over each other. 7 i 2. A means of zeroing a smaller caliber weapon as set forth in claim 1 wherein said intermittent pulse producing infrared source and said continuous infrared emitting source are gallium arsenide phosphide diodes.

3. A means of zeroing a small caliber weapon as set forth in claim 2 wherein said optics is a catadioptic optical system.

4. A means of zeroing a small caliber weapon as set forth in claim 3 wherein said catadioptic system has a diameter of 50 millimeters and one quarter degree beam spread.

5. A means of zeroing a small caliber weapon as set forth in claim 2 wherein said optics is a double convex projection lens. 1 

1. A means of zeroing a small caliber weapon at night without firing the weapon, the steps comprising: mounting an aiming light on said weapon, said aiming light has an intermittent pulse producing infrared source that produces intermittent beam of infrared illumination and optics that projects said intermittent beam of infrared illumination toward a target; inserting a tapered mandrel having a boresight alignment light mounted thereto into the muzzle end of said weapon, said boresight alignment light has a continuous infrared emitting source that produces a continuous beam of infrared illumination and optics that projects said continuous beam of infrared illuminations toward the same target; providing night viewing image intensifier goggles that are head worn by an operator wherein said goggles convert the intermittent and continuous beams of infrared illumination that is reflected from a target to visible illumination for observation by said operators; rotating said tapered mandrel through 360* within the muzzle end of said weapon and simultaneously adjusting the continuous beam of infrared illumination into a spot of reflected light signifying said continuous beam of light along the boresight of said weapon; and adjusting the direction of said intermittent beam of infrared light until said intermittent beam and said continuous beam are superimposed over each other.
 2. A means of zeroing a smaller caliber weapon as set forth in claim 1 wherein said intermittent pulse producing infrared source and said continuous infrared emitting source are gallium arsenide phosphide diodes.
 3. A means of zeroing a small caliber weapon as set forth in claim 2 wherein said optics is a catadioptic optical system.
 4. A means of zeroing a small caliber weapon as set forth in claim 3 wherein said catadioptic system has a diameter of 50 millimeters and one quarter degree beam spread.
 5. A means of zeroing a small caliber weapon as set forth in claim 2 wherein said optics is a double convex projection lens. 